EMG SNMP Agent 1.1 - User's Guide

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4. Configuration

4.1 General

EMG SNMP Agent is controlled by supplying command-line parameters and via configuration files.

Command-line parameters are used for setting agent SNMP port number (for incoming requests from SNMP managers), source port for outgoing traps and port number for incoming traps (from subagents when EMG SNMP Agent acts as a master agent).

The configuration file SNMPDIR/conf/v2managertable.cfg contains one entry for each manager to which EMG SNMP Agent should send traps.

Please note that the default port number to which SNMP agents will listen for requests from managers is 161 and that any application that binds to ports less than 1024 needs to be run as root. Often there is already an SNMP agent running on the standard SNMP port (161) preventing EMG SNMP Agent to be started on that port. In that case the master/subagent model should be used. It is recommended that EMG SNMP Agent is run as a subagent.

4.2 Changing configuration files

The configuration files in SNMPDIR/conf can be written to by the EMG SNMP Agent. Therefore it is important to stop the SNMP Agent before making any manual changes to any configuration files. After making the changes the agent should be restarted.

4.3 Basic configuration

The first important decision before configuring EMG SNMP Agent is to determine whether it should be run as a master agent or as a subagent.

4.3.1 EMG SNMP Agent as master agent (or stand-alone agent)

If no other SNMP Agent will run on the server, EMG SNMP Agent can be run using the default SNMP port (161). It is also possible for EMG SNMP Agent to act as a master agent and forward requests to subagents. Request forwarding is done based on OID and is configured in the SNMPDIR/conf/subagents.cfg file.

4.3.2 EMG SNMP Agent as subagent

Since EMG SNMP Agent is primarily designed for monitoring EMG servers it is recommended that the default operating system agent is run as the master agent, forwarding EMG-related requests to the EMG SNMP Agent. In such a scenario SNMP request forwarding is done based on OID and the EMG SNMP Agent must listen on another port than the default SNMP port (161).

When running as a subagent most of the SNMP configuration needs to be done in the master agent while the EMG SNMP Agent only needs to be configured to listen on an SNMP port other than the default. Also trap configuration always needs to be done when SNMP traps should be used.

4.4 Trap configuration

EMG SNMP Agent can be configured to send notifications to an SNMP manager when certain conditions arises, so called traps. Trap definitions are found in the MIB and generated traps will be sent to all SNMP managers as defined in the SNMPDIR/conf/v2managertable.cfg. Please note that traps can be sent to multiple destinations (managers).

Since traps are sent using the UDP protocol it is also be necessary to configure the source port for traps in the SNMPDIR/conf/agent.cfg file.

4.5 Configuration files

The configuration files support comments. Comments are lines that start with the character `#'. Since configuration files may be modifed by the agent only comments in the beginning of the file are guaranteed to be preserved. That is comments must be added before any other lines in the configuration file.

4.5.1 SNMPDIR/conf/agent.cfg

Specifies the default port numbers used by the agent. Those values can be overriden by giving command line options, run emgsnmpd -help for details.

Format is a pair key-value pair (KEY=VALUE).

Currently 3 keys are supported:

SNMP_PORT
Agent SNMP port number (default: 161)
TRAP_SOURCE_PORT
Source port (UDP) for outgoing traps (default: 8002)
INCOMING_TRAP_PORT
Port for incoming traps (default: 8004)
(Used when the agent is acting as a master agent)

Example:
SNMP_PORT=1234
TRAP_SOURCE_PORT=
INCOMING_TRAP_PORT=8084.

4.5.2 SNMPDIR/conf/servertable.cfg

Specifies which server should be monitored by the SNMP agent.

Format is one entry per line, where each entry consists of the fields specified below and separated by semicolon, ";".

server name
IP address
port number
admin state
max number of orphans
username
password
polling interval in hundredths (1/100) of a second

4.5.3 SNMPDIR/conf/subagents.cfg

Specifies subagents for request forwarding when EMG SNMP Agent is run as a master agent.

Format is one entry per line, where each entry consists of fields separated by semicolon, ";".

See the provided Adventnet AGENT-CONFIG-MIB for details.

4.5.4 SNMPDIR/conf/v2managertable.cfg

Specifies the SNMP managers to which traps will be sent.

Format is one entry per line, where each entry consists of the fields specified below and separated by semicolon, ";".

host
port
community
timeout
retries
status

4.5.5 SNMPDIR/conf/system/connectorthresholds.cfg

This file is automatically generated when SNMP agent connects to an EMG server.

Specifies the connector thresholds to be used.

Format is one entry per line, where each entry consists of the fields specified below and separated by semicolon, ";".

servername
connectorname
queue size
throughput avg A
throughput avg B
throughput avg C
max number of instances used

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